HP Cisco MDS 9020 Cisco MDS 9000 Family Fabric Manager Configuration Guide - R - Page 1113

Chapter 50 Configuring iSCSI Configuring iSLB Send documentation comments to [email protected] Caution A Gigabit Ethernet interface configured for iSLB can only be in one VRRP group because redirected sessions do not carry information about the VRRP IP address or group. This restriction allows the slave port to uniquely identify the VRRP group to which it belongs. Changing iSCSI Interface Parameters and the Impact on Load Balancing All iSCSI interfaces in a VRRP group that has load balancing enabled must have the same interface VSAN, authentication, proxy initiator mode, and forwarding mode. When you need to change any of these parameters for the iSCSI interfaces in a VRRP group, you must do so one interface at a time. During the transition time when the parameter is changed on some interfaces in the VRRP group and not the others, the master port does not redirect new initiators and instead handles them locally. Caution Changing the VSAN, proxy initiator, authentication, and forwarding mode for iSCSI interfaces in a VRRP group can cause sessions to go down multiple times. VRRP Load Balancing Algorithm For Selecting Gigabit Ethernet Interfaces When the VRRP master receives an iSCSI session request from an initiator, it first checks for an existing mapping to one of the interfaces in that VRRP group. If such a mapping exists, the VRRP master redirects the initiator to that interface. If no such mapping exists, the VRRP master selects the least loaded interface and updates the selected interface's load with the initiator's iSLB metric (weight). Note The VRRP master interface is treated specially and it takes lower load compared to the other interfaces. This is to account for the redirection work performed by the master interface for every session. A new initiator is assigned to the master interface only if the following is true for every other interface: VRRP backup interface load > [2 * VRRP master interface load + 1] Configuring Load Balancing Using VRRP You must first configure VRRP on the Gigabit Ethernet interfaces on the switch that connect to the IP network before configuring VRRP for iSLB. For information on how to configure VRRP on a Gigabit Ethernet interface, see the "Virtual Router Redundancy Protocol" section on page 51-8. To configure VRRP load balancing using Device Manager, follow these steps: Step 1 Step 2 Step 3 Choose IP > iSCSI iSLB. You see the iSCSI iSLB dialog box (see Figure 50-30). Click the VRRP tab. Click Create to configure VRRP load balancing for iSLB initiators. You see the Create iSCSI iSLB VRRP dialog box shown in Figure 50-34. OL-17256-03, Cisco MDS NX-OS Release 4.x Cisco MDS 9000 Family Fabric Manager Configuration Guide 50-45